The present invention pertains to an air lock for introducing workpieces to and/or removing them from atmospherically separated chambers with at least one transfer channel connecting the chambers.
Air locks of this class are known, for instance, from German Patent Application No. P 27 47 061. This conventional air lock serves to introduce endless carrier belts which are to be coated in a vacuum chamber by means of the air lock from the surrounding outer area having normal pressure into the coating chamber and removing them from the coating chamber after the coating process is finished. The pressure difference between the external atmospheric pressure and the usual vacuum pressure for vacuum-supported coating processes of at most 10.sup.-3 mbar is maintained over a pressure stage path which features several shutters arranged in succession, through which the carrier belt is guided. Essential elements of these so-called belt transfer channels, which bridge the pressure difference with respect to the pressure in the actual coating chamber, are the shutters constructed as slits or gaps, which oppose a significant resistance to air flow, so that the desired pressure differential is possible using vacuum pumps.
In order to guarantee a sufficient atmospheric separation between the coating chamber and the outer chamber, it is necessary to adapt the shutters to the profile of the carrier belt in order to prevent the passage, for instance, of air into the coating chamber.
Another restriction of such an air lock is that the carrier belt itself is necessary for the sealing function of the shutters, so that it is necessary that the carrier belt be led through the air lock exclusively in an endless manner in order to prevent a rise of pressure in the coating chamber. This sharply restricts the use of this known air lock in regard to the workpieces that can be transported through the transfer channel.
An object of the present invention is to create an air lock for this technology that permits a continuous transport of workpieces between two chambers, the two chambers being atmospherically separated from one another, but does not display the disadvantageous restrictions mentioned above.